Laminated magnetron constructions



June 3, 1958 A A. 1:. LA RUE LAMINATED MAGNETRON CONSTRUCTIONS 2Sheets-Sheet 1 Filed Oct. 7. 1954 INVENTOR I ALBERT D. LARuE v T NEVJune 3, 1958 A. D. LA RUE 2,837,696

LAMINATED MAGNETRON CONSTRUCTIONS Filed Oct. 7, 1954' I I 2 Sheets-Sheet2 @Q m A v LEE/2T A U5 @6 By g y TTORNE V United States Patent '0 MLAMINATED MAGNETRON CONSTRUCTIONS Albert D. La l lue, Lexington, Mass.,assignor to Raytheon Manufacturing Company, Waltham, Masa, a corporationof Delaware Application October 7, 1954, Serial No. 460,982

4 Claims. (Cl. 315-39.75)

This invention relates to an electron discharge device, and moreparticularly to electron discharge devices of the so-called magnetrontype, which are adapted to generate electrical oscillations having awave length of the order of a few centimeters or less.

Devices of this kind are intended to oscillate in a predeterminedprimary mode so as to generate a predetermined frequency, and usuallycomprise a plurality of arms called vanes, each pair of which bound acavity and form an inductance. Each pair of vanes also hasjuxtapositioned surfaces forming a capacitance. Difiiculty has beenencountered in that additional modes of oscillations have occurred,these being related to the multitank circuit system employed. Theseadditional modes are, in effect, spurious oscillations, consuming energyand reducing the efficiency of the device. It has been found that byconnecting alternate arms in a manner called strapping, the spuriousoscillations are greatly reduced. As heretofore constructed, the meansfor reducing the spurious oscillations involved certain difiicult, aswell as expensive, machining operations. This was due to the fact that,after the anode was assembled, an annular groove would be machined inthe anode and then pre- This operation was anode construction ofmagnetrons particularly with respect to the laminated type ofconstruction.

An object of the invention is to provide an improved anode constructionin which the anode straps are prestamped as part of the laminations usedin constructing the anode. This type of construction allows the strapsto be placed in any position in the anode. There is an additionaladvantage in that both straps can have the same diameter and besymmetrical in design.

A further object of this invention is to include an opening in thelaminated sections of the anode to form openings for the passage of acooling medium.

The foregoing and other objects and features of the invention will bemade fully apparent to those skilled in the art from a consideration ofthe following detailed description taken in conjunction with theaccompanying drawings in which: i

Fig. 1 is a top view of an embodiment of a magnetron constructed inaccordance with this invention;

Fig. 2 is a section taken along line 22 of Fig. 1;

Fig. 3 is a section taken along line 33 of Fig. 1;

Fig. 4 is a section taken along line 44 of Fig. 1;

Fig. 5 is a series of diagrams illustrating how the straps areconstructed as part of the laminations;

Fig. 6 is a development drawing of the anode illustrated in Fig. 1; and

Fig. 7 is a sectional view of another embodiment of a magnetronconstructed in accordance with this invention.

Referring now to Figs. 1, 2, 3 and 4, there is shown for the purpose ofillustration only an embodiment of a magnetron wherein the laminatedanode has been constructed using the center-strap design. The magnetronillustrated 2,837,696 Fatented June 3, 1958 in Fig. 1 consists of anenvelope structure 10 which formsthe anode 11 of the magnetron. Undernormal operation the oscillations are generated at a frequency which isdetermined by the geometry of the vanes 12 and the cavity resonators 13located therebetween. These oscillations are picked up by a couplingdevice 14 which is adapted to feed any suitable utilizing device.-

As pointed out above, heretofore the straps for a laminated anode had tobe pre-assernbled and the anode carefully machined or routed where thestraps were to be placed. After'placing the straps in position it wasthen necessary to solder the straps to the proper vanes. At very bestthis operation could be used for straps placed on the end section of theanode. It has long been recognized that a center-strapped anode has moreadvantages over end-strapped anodes, in that the straps could beelectrically balanced, symmetrical, and have reduced coupling betweenthe strap and the end section of the anode. Heretofore, a symmetricalcenter strapped anode could not be built for a completely laminatedanode.

In accordance with the present invention the anode 11 is constructed ofall stamped parts. Anode 11 is made up of a plurality of flat stampedlaminations 15, 16, 17,

18, 19 and 20 preferably constructed of high conductivity copper and inthe form as illustrated in Fig. 5.

Each lamination is formed with a center opening 21 and a plurality ofradial slots 22 each terminating in the center opening 21. Theinterconnections between alternate vanes are made substantially alongthe central portion of the anode faces by means of conducting straps 23and 24. As illustrated in Fig. 6, strap 23 electrically interconnectsvanes 25, 26, 27, and 28 while the intervening vanes 29, 30, 31 and 32have their faces provided with a slot through which strap 23 passesfreely so as to avoid electrical contact with said intervening vanes.Likewise the strap 24 is electrically connected to the vanes 29, 30, 31and 32, while the faces of vanes 25, 26, 27 and 28 are provided withslots which permit the strap 24 to pass through without coming intoelectrical contact with the intervening vane faces. Theseinterconnections on straps between alternate vanes substantiallyeliminate the tendency for transverse spurious modes of oscillations tooccur. The complete method of strapping a full 8-vane anode isillustrated in Fig. 6. It is well known that such strapping not onlysubstantially eliminates spurious transverse modes but will alsosubstantially elimihate the spurious longitudinal modes.

Fig. 3 represents a cross-sectional view of vanes 29, 30, 31 and 32 andFig. 4 represents a cross-sectional view of vanes 25, 26, 27 and 28. Theanode 11 is built up of the basic lamina sections 15, 16, 17, 18, 19 and20 stacked so as to attain the type of strapping desired. In order tobuild up the cross-sectional view illustrated in Figs.

3 and 4, it is necessary to use the following stampings in assemblingfrom top to bottom:

Lamination 15 is a circular strapping having a large central hole and isused for building up the end section of the anode. Laminations 17, 18,19, and 20 have identical holes 33 punched near the peripheries of thelaminations so as to provide a passage 34 in the comnation 18 has everyother vane shortened a given amount in order to provide clearance in aradial direction for straps 23 and 24. Lamination 19 contains the strapsjoining every other vane. The vanes not so joined are cut back a givenamount to provide clearance in a radial direction for the straps 23 and24. Lamination 20 has all the vanes cut back a given amount to provideclearance in a vertical direction between straps 23 and 24. It isapparent in building up an anode section that lamina 18 and 19 are usedtwice. Lamination 19 is used twice in order to obtain both straps 23 and24 and lamination 18 is used to obtain the necessary clearance betweenthe straps and the vanes. To obtain both straps it is only necessary tooiiset lamination 19 by one vanes position. It is for this reason thatFig. does not have the vanes numbered. After assembly of the anodesection, a facing 35 is applied to all the vanes in order to protect thestrapping from electron bombardment. Facing 35 is preferably constructedfrom a silver utectic material so as to form a silver braze covering thevanes as illustrated.

It will be apparent to those skilled in the art that the present methodof having the straps constructed as part of the lamination is adaptableto be used for any strapping design incorporated in laminated anodeconstruction.

Of course it is to be understood that this invention is not limited tothe particular details as described above as many equivalents willsuggest themselves to those skilled in the art. For example, Fig. 7illustrates an unsymmetrical method of double strapping a laminatedanode wherein both straps are placed at one end of the anode. It isentirely conceivable that a single strap may be placed at each end ofthe anode. These and many other ways of strapping an anode by means ofprestamped laminations will suggest themselves to those men skilled inthe 'art. In each instance, by utilizing the principles of the inventionas enunciated herein, it will be possible to construct strapped anodesof any desired form and shape and thus remove spurious modes ofoscillations in a more economical manner than has been possible to date.

What is claimed is:

1. An electron discharge device comprising a laminated anode constructedof a plurality of individual laminations, said anode having a pluralityof vanes of substantial length and adapted to have oscillations set uptherein, and a facing material for each vane thereby protecting saidlaminations from electron bombardment.

2. Electron discharge device comprising a laminating anode constructedfrom a plurality of individual laminations, said anode having aplurality of vanes of substantial length and adapted to havingoscillations set up therein, interconnecting straps punched out of thesame laminations used to assemble the anode for electrically connectingalternate vanes, and a facing material for each vane electricallyinterconnecting laminations forming said vane.

3. An electron discharge device comprising a laminated anode constructedfrom a plurality of individual laminations, said anode having aplurality of vanes of substantial length and adapted to haveoscillations set up therein, strapping means electricallyinterconnecting alternate vanes, means for facing each vane thereby protecting said strapping means and said laminations from electronbombardment, and a passage located in said anode for cooling said anode,said strapping means and said cooling passage constructed as part of thesame lamination used to assemble the anode.

4. An electron discharge device comprising a laminated anode constructedfrom a plurality of individual laminations, said anode having aplurality of vanes of substantial length and adapted to haveoscillations set up therein, interconnecting straps punched out of thesame laminations used to assemble the anode for electrically connectingalternate vanes, a facing material for each vane electricallyinterconnecting the laminations forming said vane, and a cooling passagepunched out of the same lamination used to assemble the anode.

References Cited in the file of this patent UNITED STATES PATENTS2,444,080 Williams June 29, 1948 2,477,122 Garner July 26, 19492,547,503 Smith Apr. 3, 1951 2,583,793 Nelson Ian. 29, 1952

